Water absorbent materials, such as superabsorbent polymers, can be employed in various applications such as in disposable hygiene articles (e.g. diapers, incontinence articles, feminine hygiene products airlaids and absorbent dressings); household articles; sealing materials; in oil-drilling fluids (e.g. lost-circulation material, fracturing fluids); anti-condensation coatings; in agricultural, horticultural and forestry applications for retaining water in the soil and for the release of water to the roots of plants and trees; in the textile industry; in printing applications; in absorbent paper products; in bandages and surgical pads (e.g. wound dressings); in ore treatments; in concrete products; in pet litter; in water treatment; in food pads (e.g. applications related to the transportation of fresh food and food packaging); in detergents; in fire-fighting gels; in cloud control; as chemical absorbents for the cleanup of acidic and/or basic aqueous spills including water soluble chemical spills; as polymeric gels for the slow and controlled release of cosmetics and pharmaceuticals (also known as drug delivery systems); and in the manufacture of artificial snow. However, the primary use of superabsorbent polymers, also referred as “SAPs”, resides in disposable personal hygiene articles. Such products include, in decreasing order of volume of superabsorbent materials used, diapers, training pants, adult incontinence products and feminine hygiene products.
Carboxyalkyl polysaccharides have been disclosed as superabsorbent materials by Ning et al. U.S. Pat. No. 5,247,072; Qin et al. U.S. Pat. Nos. 5,470,964; 5,498,705; 5,550,189; WO 01/87365; and Wallajapet et al. US App. 2006/0147689. However, in addition to being costly, the absorption characteristics of such materials were often insufficient to be useful in the hygiene industry. As a result, synthetic superabsorbent materials such as polyacrylates have experienced rapid development.
The “Absorbency Under Load” (AUL), as measured at 0.7 psi, constitutes a widely recognized indicator characterizing to the absorption efficiency of a superabsorbent material. Carboxyalkyl polysaccharides exhibiting high AUL values have been previously disclosed by Mertens et al. (US App. 2004/0157734). However, Mertens is silent with respect to the biobased content and the carboxyalkylation pattern of the polysaccharides disclosed. Moreover, Mertens is silent with respect to the carboxyalkylation process used to manufacture the materials disclosed.
Carboxyalkylated starches, produced by means of aqueous processes, have been previously disclosed by Gross et al. U.S. Pat. No. 5,079,354; Couture et al. CA 2,362,006; and Theodorus et al. NL 9100249. However, the carboxyalkylated starches were not disclosed as having high AUL values.
The present disclosure refers to a number of documents, the content of which is herein incorporated by reference in their entirety.